Valve timing adjustment apparatus

ABSTRACT

A main locking mechanism locks a phase at a main locking phase, at which an intake valve is closed at timing later than a bottom dead center, by inserting a main locking member into a main locking hole. A sub locking mechanism locks a phase at a sub locking phase advanced more than the main locking phase by inserting a sub locking member into a sub locking hole. A movable body disposed in the main locking hole reciprocates between an open position and a blocking position of the main locking hole. During a warm start of an engine, a driving source maintains the movable body at the open position at which the inserting of the main locking member into the main locking hole is maintained. In contrast, during a cold start of the engine, the driving source drives the movable body to the blocking position at which the main locking member is removed from the main locking hole.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese Patent Application No. 2013-124062 filed on Jun. 12, 2013.

TECHNICAL FIELD

The present invention relates to a valve timing adjustment apparatusthat adjusts valve timing of an intake valve which opens and closes acylinder of an internal combustion engine.

BACKGROUND

In the related art, a hydraulic valve timing adjustment apparatus whichadjusts valve timing of an intake valve using a pressure of a workingfluid is widely known. Typically, the hydraulic valve timing adjustmentapparatus includes a housing rotor and a vane rotor which rotaterespectively in connection with a crank shaft and a cam shaft of aninternal combustion engine, and when the vane rotor in the housing rotorreceives a pressure of the working fluid, a relative rotational phasebetween the rotors changes. As a result of the change of the relativerotational phase, the valve timing is adjusted.

A Japanese patent document 1 (JP 4,161,356 B) discloses a type of thehydraulic valve timing adjustment apparatus of the internal combustionengine in which a rotational phase advanced more than the most retardedangle phase is regarded as an intermediate phase. When a rotationalphase reaches the intermediate phase, the rotational phase is lockedduring the starting of the internal combustion engine. The closingtiming of the intake valve becomes as quickly as possible by the lockingfunction. As a result, an actual compression ratio of the cylinderincreases and a temperature of gas in the cylinder increases bycompression heating, and thus, fuel vaporization is promoted.Accordingly, startability can be ensured during the cold start of theinternal combustion engine that is left in a stop state under a lowtemperature condition such as an extremely low temperature condition.

However, in the hydraulic valve timing adjustment apparatus with earlyclosing timing of the intake valve disclosed in the patent document 1,there is a concern in that the following problems may occur due to theactual high compression ratio of the cylinder during the warm start ofthe internal combustion engine under a comparatively high temperaturecondition such as a normal temperature condition. One of the problems isoccurrence of knocking. Another problem occurs during the re-starting ofthe internal combustion engine applied to an idle stop system or ahybrid system, or during the re-starting of the engine immediately afteran engine is stopped by a turn-off of an ignition switch. A temperatureof gas in the cylinder excessively increases during compression, therebycausing pre-ignition in which the gas undergoes self-ignition beforebeing ignited, or a compressive reaction force becomes great andvariation of a cranking rotation increases, thereby causing anunpleasant vibration or a noise.

In addition, a hydraulic valve timing adjustment apparatus disclosed ina patent document 2 (JP 2002-256910 A) selects one of the following twophases during the starting of the internal combustion engine: a retardedangle phase set so as to close the intake valve at timing later thanwhen a piston reaches a bottom dead center of the cylinder; and anintermediate phase advanced more than the retarded angle phase. A startoptimized for a temperature (hereinafter, referred to as an “enginetemperature”) of the internal combustion engine can be ensured by theselection of the rotational phase.

In the hydraulic valve timing adjustment apparatus disclosed in thepatent document 2, a pressure of the working fluid is imparted on thevane rotor in the housing rotor during the warm start of the internalcombustion engine. Accordingly, the rotational phase is not locked, andthe retarded angle phase is selected by the adjustment of the rotationalphase. For this reason, during the start during which the pressure ofthe working fluid is reduced, the vane rotor rotates to advance relativeto the housing rotor by a variable torque from the cam shaft, and therotational phase is likely to shift from the retarded angle phase.

In the hydraulic valve timing adjustment apparatus disclosed in thepatent document 2, since a variable torque causes the rotational phaseto change to the intermediate phase during the cold start of theinternal combustion engine, the working fluid imparting a pressure onthe vane rotor in the housing rotor is drained. As a result, the workingfluid imparting a pressure on a locking body is also drained.Accordingly, the locking body moves to a locking release position, andthe rotational phase is difficult to be locked at the intermediatephase.

SUMMARY

The present disclosure is made in light of the problems described above,and an object of the present disclosure is to provide a hydraulic valvetiming adjustment apparatus with which an engine start optimized for anengine temperature is realized.

In a first aspect of the present disclosure, a valve timing adjustmentapparatus that adjusts valve timing of an intake valve, which opens andcloses a cylinder of an internal combustion engine, by a pressure of aworking fluid. The valve timing adjustment apparatus includes a housingrotor that rotates in connection with a crank shaft of the internalcombustion engine and a vane rotor that rotates in connection with a camshaft of the internal combustion engine. A rotational phase of the vanerotor relative to the housing rotor is changed by receiving the pressureof the working fluid in the housing rotor. The apparatus furtherincludes a main locking portion that has a main locking member and amain locking hole. The main locking portion locks the rotational phaseto a main locking phase, at which the intake valve is closed at timinglater than when a piston in the cylinder reaches a bottom dead center ofthe cylinder, by inserting the main locking member into the main lockinghole when the rotational phase is the main locking phase during thestarting of the internal combustion engine. A sub locking portion has asub locking member and a sub locking hole. The sub locking portion locksthe rotational phase to a sub locking phase, which is advanced more thanthe main locking phase, by inserting the sub locking member into the sublocking hole when the rotational phase is changed from the main lockingphase to the sub locking phase during the starting of the internalcombustion engine. A movable body is disposed in the main locking holeto reciprocate between an open position at which the movable body opensthe main locking hole and a blocking position at which the movable bodyblocks the main locking hole. A determination portion determines a warmstart when a temperature of the internal combustion engine is equal toor higher than a specific temperature and a cold start when atemperature of the internal combustion engine is lower than the specifictemperature. A driving source maintains the movable body at the openposition, at which the main locking member is inserted into the mainlocking hole, when the determination portion determines the warm start,and drives the movable body to the blocking position, at which the mainlocking member is removed from the main locking hole, when thedetermination portion determines the cold start.

According to the first aspect the present disclosure, during the warmstart of the internal combustion engine during which it is determinedthat the engine temperature is equal to or higher than the specifictemperature, the movable body, which opens or closes the main lockinghole by reciprocating in the main locking hole, is maintained at theopen position. As a result, since the inserting of the main lockingmember into the main locking hole is maintained at the main lockingphase during the starting of the internal combustion engine, therotational phase remains locked at the main locking phase. Herein, atthe main locking phase at which the intake valve is closed at timinglater than when the piston reaches the bottom dead center of thecylinder, gas in the cylinder is pushed into an intake system as thepiston lifts up from the bottom dead center, and thus an actualcompression ratio decreases. Accordingly, during the warm start, therotational phase is retained at the main locking phase, and occurrenceof a starting failure (herein after, simply referred to as a “startingfailure”) such as knocking, pre-ignition, an unpleasant vibration or anoise is suppressed.

In contrast, during the cold start of the internal combustion engineduring which it is determined that the engine temperature is lower thanthe specific temperature, the movable body is driven to the blockingposition. Since the main locking member is removed from the main lockinghole at the main locking phase during the starting of the internalcombustion engine, the locking of the rotational phase is released. Atthis time, the vane rotor, which receives a variable torque from the camshaft, rotates in an advance direction relative to the housing rotor,and thus the rotational phase is changed to the sub locking phaseadvanced more than the main locking phase. As a result, the sub lockingmember is inserted into the sub locking hole and the rotational phase islocked at the sub locking phase, and thus a closing timing of the intakevalve becomes as quickly as possible. Accordingly, the amount of gasbeing pushed out of the cylinder decreases, and a temperature of the gasincreases together with the actual compression ratio, and thus evenduring the cold start, ignitability improves and startability can beensured.

According to the present disclosure described above, a start optimizedfor the engine temperature can be realized.

In a second aspect of the present disclosure, the movable body has aprotruding end portion that protrudes to an outside of the housing rotorfrom the main locking hole when the movable body is at the openposition. The driving source has a drive shaft disposed outside thehousing rotor that presses the protruding end portion at the openposition toward the blocking position during the cold start.

According to the second aspect of the present disclosure, during thecold start, the drive shaft outside the housing rotor presses theprotruding end portion of the movable body when the movable body is atthe open position, which protrudes to the outside of the housing rotorfrom the main locking hole. As a result, not only the movable body isreliably driven to the blocking position so that the locking of therotational phase can be released, but also the drive shaft is preventedfrom interfering with a rotation of the vane rotor in the housing rotorrelative to the housing rotor so that the rotational phase can smoothlychange to the sub locking phase. Accordingly, the time period which ittakes from when a variable torque is generated during cranking of thecold start of the internal combustion engine until when the rotationalphase is locked at the sub locking phase can be shortened, and thusreliability can be improved particularly in cold startability.

In a third aspect of the present disclosure, the housing rotor and thevane rotor rotate around an axis, and the movable body reciprocates in adirection parallel to the axis of the housing rotor and the vane rotor.The protruding end portion has a tapered outer circumferential surfacehaving a diameter that decreases toward a distal end of the protrudingend portion. The drive shaft is supported by a stationary component ofthe internal combustion engine, and the driving source withdraws thedrive shaft from a rotation region of the protruding end portion duringthe warm start and advances the drive shaft into the rotation regionduring the cold start.

According to the third aspect of the present disclosure, during the warmstart, the drive shaft withdraws from the rotation region of theprotruding end portion, and thus the movable body is not pressed by thedrive shaft and can be reliably maintained at the open position. Incontrast, during the cold start, the drive shaft supported by thestationary component of the internal combustion engine advances into therotation region of the protruding end portion, and thus the movable bodyis brought into contact with the outer circumferential surface of theprotruding end portion as the housing rotor rotates. At this time, sincethe drive shaft is brought into contact with the taper-shaped outercircumferential surface of the protruding end portion the diameter ofwhich gradually decreases toward the distal end, the movable bodyreceives a partial force from the drive shaft in the direction ofmovement of the movable body which is along the common axial directionof the housing rotor and the vane rotor, and the movable body can bereliably pressed and driven toward the blocking position. Accordingly,the movable body can accurately move to the open position at which thelocking of the rotational phase is retained at the main lockingposition, or to the blocking position at which the locking of therotational phase is released. As a result, when the rotational phase isswitched to a rotational phase optimized for each of the warm start andthe cold start, reliability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objectives, features andadvantages thereof, will be best understood from the followingdescription, the appended claims and the accompanying drawings, inwhich:

FIG. 1 is a view illustrating a basic configuration of a valve timingadjustment apparatus according to First Embodiment of the presentdisclosure, and a cross-sectional view taken along line I-I in FIG. 2;

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a cross-sectional view illustrating an operation statedifferent from the operation state in FIG. 2;

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a schematic view illustrating an operation state of the valvetiming adjustment apparatus of FIG. 1;

FIG. 6 is a schematic view illustrating an operation state differentfrom the operation state in FIG. 5 of the valve timing adjustmentapparatus of FIG. 1;

FIG. 7 is a schematic view illustrating an operation state differentfrom the operation states in FIGS. 5 and 6 of the valve timingadjustment apparatus of FIG. 1;

FIG. 8 is a schematic view illustrating an operation state differentfrom the operation states in FIGS. 5 to 7 of the valve timing adjustmentapparatus of FIG. 1;

FIG. 9 is a schematic view describing characteristics of the valvetiming adjustment apparatus of FIG. 1;

FIG. 10 is a graph describing the characteristics of the valve timingadjustment apparatus of FIG. 1;

FIG. 11 is a perspective view illustrating main parts of the valvetiming adjustment apparatus of FIG. 1;

FIG. 12 is a cross-sectional view taken along line I-I in FIG. 2 tocorrespond to the operation state in FIG. 5;

FIG. 13 is a cross-sectional view taken along line I-I in FIG. 2 tocorrespond to the operation state in FIG. 6;

FIG. 14 is a schematic view describing an operation of the valve timingadjustment apparatus of FIG. 1;

FIG. 15 is a characteristic graph describing a variable torque that actson the valve timing adjustment apparatus of FIG. 1;

FIG. 16 illustrates graphs describing an example of an operation of thevalve timing adjustment apparatus of FIG. 1;

FIG. 17 illustrates graphs describing an example of an operationdifferent from the operation in FIG. 16 of the valve timing adjustmentapparatus of FIG. 1;

FIG. 18 is a flow chart illustrating a control flow executed by thevalve timing adjustment apparatus of FIG. 1 during the starting of aninternal combustion engine;

FIG. 19 is a schematic view illustrating unique portions of a valvetiming adjustment apparatus according to Second Embodiment of thepresent disclosure;

FIG. 20 is a schematic view describing an operation of the valve timingadjustment apparatus of FIG. 19;

FIG. 21 is a schematic view describing the operation of the valve timingadjustment apparatus of FIG. 19; and

FIG. 22 is a schematic view illustrating a modification example of thevalve timing adjustment apparatus of FIG. 14.

DETAILED DESCRIPTION

Hereinafter, a plurality of embodiments of the present disclosure willbe described with reference to the accompanying drawings. There is acase where the same reference signs are assigned to the correspondingconfiguration elements in each embodiment, and duplicated descriptionsof the configuration elements will be omitted. When only a portion of aconfiguration of each embodiment is described, other portions of theconfiguration can be described using configurations of the otherembodiments, which are previously described. In the description of eachembodiment, the present disclosure is not limited only to a combinationof the configuration which is specified, but also the configurations ofthe plurality of embodiments can be partially combined even if notspecified insofar as there is no obstacle to the combination of theconfigurations.

First Embodiment

As illustrated in FIG. 1, a valve timing adjustment apparatus 1according to the First Embodiment of the present disclosure is mountedon an internal combustion engine of a vehicle. In the embodiment, theinternal combustion engine is stopped and started not only by an ONcommand or an OFF command of an engine switch SW but also by an idlestop command or a re-starting command of an idle stop system ISS.

(Basic Configuration)

First, a basic configuration of the valve timing adjustment apparatus 1will be described. The apparatus 1 is a hydraulic type that uses apressure of a working oil as a “pressure of a working fluid”, andadjusts valve timing of an intake valve 9 (refer to FIG. 10 to bedescribed later) as a “moving valve” that a cam shaft 2 opens or closesvia transmission of an engine torque. The apparatus 1 illustrated inFIGS. 1 to 8 includes a rotation drive unit 10 that is disposed in atransmission system which transmits an engine torque output from a crankshaft (not illustrated) to the cam shaft 2 in the internal combustionengine, and a control unit 40 that controls inflow and outflow of theworking oil to drive the drive unit 10.

(Rotation Drive Unit)

The rotation drive unit 10 includes rotors 11 and 14 and locking members160 and 170.

As illustrated in FIGS. 1 and 2, the metallic housing rotor 11 includesa rear plate 13 and a front plate 15 that are respectively tightenedwith each end portion of a shoe ring 12 in an axial direction. The rearplate 13 has cylindrical locking holes 162 and 172 formed to be opentoward the vane rotor 14 within the shoe ring 12.

The shoe ring 12 has a cylindrical housing main body 120, a plurality ofshoes 121, 122 and 123 and a sprocket 124. As illustrated in FIG. 2, theshoes 121, 122 and 123 protrude inward in a radial direction fromlocations of the housing main body 120, which are apart in a rotationaldirection with a predetermined gap therebetween. Accommodation chambers20 are respectively formed between the shoes 121 and 122, the shoes 122and 123, and the shoes 123 and 121 each pair of which is adjacent in therotational direction to each other. The sprocket 124 is connected to thecrank shaft via a timing chain (not illustrated). Through thisconnection, an engine torque is transmitted from the crank shaft to thesprocket 124 while the internal combustion engine rotates. Accordingly,the housing rotor 11 rotates in a constant direction (in a clockwisedirection in FIG. 2) in connection with the crank shaft.

As illustrated in FIGS. 1 and 2, the metallic vane rotor 14 is coaxiallyhoused inside the housing rotor 11. The metallic vane rotor 14 and thehousing rotor 11 rotate around an axis. Both end portions in the axialdirection of the vane rotor 14 slide against the rear plate 13 and thefront plate 15, respectively. The vane rotor 14 has a cylindrical rotaryshaft 140 and a plurality of vanes 141, 142 and 143. The rotary shaft140 is coaxially fixed to the cam shaft 2. With this, the vane rotor 14can rotate in connection with the cam shaft 2 in the same direction (inthe clockwise direction in FIG. 2) as that of the housing rotor 11, andthe vane rotor 14 can rotate relative to the housing rotor 11.

As illustrated in FIG. 2, the vanes 141, 142 and 143 protrude outward inthe radial direction from locations of the rotary shaft 140, which areapart in the rotational direction with a predetermined gap therebetween,and each of the vanes 141, 142 and 143 is housed in the correspondingaccommodation chamber 20. Each of the vanes 141, 142 and 143 divides thecorresponding accommodation chamber 20 in the rotational direction, andpartitions advance chambers 22, 23 and 24 which the working oil flowsinto or out of and retard chambers 26, 27 and 28 which the working oilflows into or out of in the housing rotor 11. Specifically, the advancechamber 22 is formed between the shoe 121 and the vane 141, the advancechamber 23 is formed between the shoe 122 and the vane 142, and theadvance chamber 24 is formed between the shoe 123 and the vane 143. Theretard chamber 26 is formed between the shoe 122 and the vane 141, theretard chamber 27 is formed between the shoe 123 and the vane 142, andthe retard chamber 28 is formed between the shoe 121 and the vane 143.

As illustrated in FIGS. 1 and 2, the vane 141 supports the cylindricalmetallic main locking member 160 in such a manner that the main lockingmember 160 can reciprocate in a direction parallel to the axis of therotors 11 and 14. In addition, the vane 141 forms a main locking releasechamber 161 around the main locking member 160. The main locking releasechamber 16 is an annular space which the working oil flows into or outof. As illustrated in FIGS. 1 and 5, when the working oil is dischargedout of the main locking release chamber 161, the main locking member 160is inserted into the main locking hole 162. The main locking member 160locks a rotational phase (hereinafter, simply referred to as a“rotational phase”) of the vane rotor 14 relative to the housing rotor11 at a main locking phase Pm by the inserting. In contrast, asillustrated in FIGS. 6 to 8, the main locking member 160 is removed fromthe main locking hole 162 by receiving a pressure of the working oilintroduced into the main locking release chamber 161. The main lockingmember 160 releases the rotational phase locked at the main lockingphase Pm when the main locking member 160 is removed from the mainlocking hole 162.

As illustrated in FIGS. 3 and 4, the vane 142 supports the cylindricalmetallic sub locking member 170 in such a manner that the sub lockingmember 170 can reciprocate in a direction parallel to the axis of therotors 11 and 14. The vane 142 forms a sub locking release chamber 171around the sub locking member 170. The sub locking release chamber 171is an annular space which the working oil flows into or out of. Asillustrated in FIGS. 4 and 7, when the working oil is discharged out ofthe sub locking release chamber 171, the sub locking member 170 isinserted into the sub locking hole 172. The sub locking member 170 locksa rotational phase of the vane rotor 14 at a sub locking phase Ps whenthe sub locking member 170 is inserted into the sub locking hole 172. Incontrast, as illustrated in FIGS. 5, 6 and 8, the sub locking member 170is removed from the sub locking hole 172 by receiving a pressure of theworking oil introduced into the sub locking release chamber 171. The sublocking member 170 releases the rotational phase locked at the sublocking phase Ps when the sub locking member 170 is removed from the sublocking hole 172.

In the rotation drive unit 10, when the vane rotor 14 in the housingrotor 11 receives a pressure of the working oil flowing into or out ofthe advance chambers 22, 23 and 24 and the retard chambers 26, 27 and 28under the release of the locking of the rotational phase, valve timingis adjusted. Specifically, when the working oil is introduced into theadvance chambers 22, 23 and 24, and the working oil is discharged out ofthe retard chambers 26, 27 and 28, the rotational phase changes toadvance (for example, a change from a state in FIG. 2 to a state in FIG.3). As a result, the valve timing is adjusted to advance. When theworking oil is introduced into the retard chambers 26, 27 and 28, andthe working oil is discharged out of the advance chambers 22, 23 and 24,the rotational phase changes to retard (for example, a change from thestate in FIG. 3 to the state in FIG. 2). As a result, the valve timingis adjusted to retard. When the working oil is enclosed in the advancechambers 22, 23 and 24, and the retard chambers 26, 27 and 28, a changeof the rotational phase is suppressed, and the valve timing is adjustedto be retained at a substantially constant value.

(Control Unit)

As illustrated in FIGS. 1 and 5, the control unit 40 includes passages41, 45, 49, 50, 52 and 54, a control valve 60 and a control circuit 80.

The main advance passage 41 is formed in the rotary shaft 140, andcommunicates with the advance chambers 22, 23 and 24. The main retardpassage 45 is formed in the rotary shaft 140, and communicates with theretard chambers 26, 27 and 28. The locking release passage 49 is formedin the rotary shaft 140, and communicates with both of the lockingrelease chambers 161 and 171.

The main supply passage 50 is formed in the rotary shaft 140, andcommunicates with a pump 4 as a supply source via a transportationpassage 3. Herein, the pump 4 is a mechanical pump that is driven byreceiving an engine torque during the rotation of the internalcombustion engine. The pump 4 continuously discharges the working oilsuctioned from a drain pan 5 during the rotation. The transportationpassage 3 passes through the cam shaft 2 and a bearing thereof, and canalways communicate with a discharge port of the pump 4 regardless ofrotation of the cam shaft 2. In such a configuration, when the internalcombustion engine starts by cranking to reach a complete combustion, thepump 4 starts supplying the working oil to the main supply passage 50.In contrast, when the internal combustion engine is stopped, the supplyof the working oil is stopped.

The sub supply passage 52 is formed in the rotary shaft 140, andbranches from the main supply passage 50. The sub supply passage 52receives the working oil supplied from the pump 4 via the main supplypassage 50. The drainage recovery passage 54 is provided outside therotation drive unit 10 and the cam shaft 2. The drainage recoverypassage 54 and the drain pan 5 as a drainage recovery unit are open tothe air, and the working oil can be discharged to the drain pan 5.

In the embodiment, the control valve 60 is an electromagnetic spoolvalve. The control valve 60 makes use of a driving force which isgenerated by energizing a linear solenoid 62 and a restoring force whichis generated in opposition to a direction of the driving force by anelastic deformation of a biasing member 64. The control valve 60connecting to each of the passages 41, 45, 49, 50, 52 and 54 switchescommunication between the passages by reciprocating in the axialdirection a spool 68 inside a sleeve 66 illustrated in FIGS. 1 and 2.Specifically, when the spool 68 moves to a locking region R1 which isillustrated in FIGS. 5 to 7, the working oil is introduced from the pump4 into the retard chambers 26, 27 and 28, and the working oil in theadvance chambers 22, 23 and 24 and the locking release chambers 161 and171 is discharged to the drain pan 5. When the spool 68 moves to aretard region Rr which is illustrated in FIG. 8, the working oil in theadvance chambers 22, 23 and 24 is discharged to the drain pan 5, and theworking oil is introduced from the pump 4 into the retard chambers 26,27, 28 and the locking release chambers 161 and 171. When the spool 68moves to an advance region Ra which is illustrated in FIG. 8, theworking oil in the retard chambers 26, 27 and 28 is discharged to thedrain pan 5, and the working oil is introduced from the pump 4 into theadvance chambers 22, 23, 24 and the locking release chambers 161 and171. When the spool 68 moves to a retention region Rh which isillustrated in FIG. 8, the working oil is introduced from the pump 4into the locking release chambers 161 and 171, and the working oil isenclosed in the advance chambers 22, 23 and 24 and the retard chambers26, 27 and 28.

The control circuit 80 is a micro computer that is electricallyconnected to the linear solenoid 62, the engine switch SW, variouselectrical components of the internal combustion engine and the like asillustrated in FIG. 1. The control circuit 80 is a configurationcomponent of the idle stop system ISS. The control circuit 80 controlsthe energization of the linear solenoid 62 and an operation of theinternal combustion engine, which includes idle stop, based on acomputer program.

(Main Locking Mechanism)

Subsequently, a main locking mechanism 16 illustrated in FIG. 1 as “mainlocking portion” will be described. The main locking mechanism 16includes a main elastic member 163, which is provided in the rotationdrive unit 10 and combined with a set of the main locking elements 160,161 and 162.

As illustrated in FIG. 5, the main elastic member 163 is a metallic coilspring, and is housed in the vane 141. The main elastic member 163 isinstalled between spring receiving portions 141 a and 160 a which arerespectively provided in the vane 141 and the main locking member 160.Since the main elastic member 163 is installed between the springreceiving portions 141 a and 160 a, the main elastic member 163generates a restoring force to bias the main locking member 160 towardthe rear plate 13. Accordingly, a restoring force of the main elasticmember 163 at the main locking phase Pm as illustrated in FIGS. 5 and 6becomes a biasing force that acts in a direction in which the mainlocking member 160 is inserted into the main locking hole 162. A drivingforce caused by a pressure in the main locking release chamber 161drives the main locking member 160 against the restoring force of themain elastic member 163, and the driving force at the main locking phasePm acts in a direction in which the main locking member 160 is removedfrom the main locking hole 162.

In the aforementioned configuration, the main locking phase Pm whichoccurs by inserting the main locking member 160 into the main lockinghole 162 is preset to the most retard angle phase as illustrated inFIGS. 2 and 9. As illustrated in FIG. 10, the main locking phase Pmparticularly in the embodiment is preset to a rotational phase at whichthe intake valve 9 is closed at timing later than when a piston 8reaches a bottom dead center BDC in a cylinder 7 of the internalcombustion engine.

(Sub Locking Mechanism)

Subsequently, a sub locking mechanism 17 which is illustrated in FIG. 4as “sub locking portion” will be described. The sub locking mechanism 17is constituted by combining a sub elastic member 173 and a limitinggroove 174, which are provided in the rotation drive unit 10, into a setof the sub locking elements 170, 171 and 172.

As illustrated in FIG. 5, the sub elastic member 173 is a metallic coilspring, and is housed in the vane 142. The sub elastic member 173 isinstalled between spring receiving portions 142 a and 170 a which arerespectively provided in the vane 142 and the sub locking member 170.Since the sub elastic member 173 is installed between the springreceiving portions 142 a and 170 a, the sub elastic member 173 generatesa restoring force to bias the sub locking member 170 toward the rearplate 13. Accordingly, a restoring force of the sub elastic member 173at the sub locking phase Ps illustrated in FIGS. 7 and 8 serves as abiasing force that acts in a direction in which the sub locking member170 is inserted into the sub locking hole 172. A driving force caused bya pressure in the sub locking release chamber 171 drives the sub lockingmember 170 against the restoring force of the sub elastic member 173,and the driving force at the sub locking phase Ps acts in a direction inwhich the sub locking member 170 is removed from the sub locking hole172.

As illustrated in FIGS. 2, 3 and 5, the limiting groove 174 is formed onthe rear plate 13 in a bottomed long hole shape, and extends in acircular arc shape along the common rotational direction of the rotors11 and 14. The sub locking hole 172 is opened in a groove bottom of anintermediate portion of the limiting groove 174. When the sub lockingmember 170 enters into the limiting groove 174 from both sides in therotational direction of the sub locking hole 172, an opening structureof the sub locking hole 172 limits a rotational phase within a givenrotational phase region within which the sub locking phase Ps isinterposed. When the rotational phase reaches the sub locking phase Ps,the sub locking member 170 is inserted into the sub locking hole 172within the limiting groove 174, whereby locking the rotational phase atthe sub locking phase Ps as illustrated in FIG. 7.

In the aforementioned configuration, the sub locking phase Ps realizedby inserting the sub locking member 170 into the sub locking hole 172 ispreset to the intermediate phase advanced more than the main lockingphase Pm as illustrated in FIGS. 3 and 9. As illustrated in FIG. 10, thesub locking phase Ps particularly in the embodiment is preset to arotational phase for closing the intake valve 9 at timing when thepiston 8 reaches the bottom dead center BDC of the cylinder 7 of theinternal combustion engine or at timing when the piston 8 reaches thevicinity of the bottom dead center BDC.

(Locking Control System)

Subsequently, a locking control system 18 which is illustrated in FIG. 1will be described. The locking control system 18 includes a movable body181, which is provided in the rotation drive unit 10, and a drivingsource 182 provided in the control unit 40 into the control circuit 80.

The columnar metallic movable body 181 is coaxially disposed within themain locking hole 162, and can reciprocate in a direction parallel tothe axis of the rotors 11 and 14. Herein, as illustrated in FIGS. 5, 11and 12, the main locking hole 162 passes through the rear plate 13 andis also opened to a side opposite to the vane rotor 14. The movable body181 protrudes toward the outside of the housing rotor 11 from the mainlocking hole 162 via an opening 162 a on the opposite side. Accordingly,one end portion of the movable body 181 forms a protruding end portion183 which protrudes to the outside of the housing rotor 11 at a movingposition. In the embodiment, the protruding end portion 183 has ataper-shaped (cone-shaped) outer circumferential surface 183 a having adiameter that gradually decreases toward the distal end.

As illustrated in FIGS. 5 and 12, the other end portion of the movablebody 181 forms a housed end portion 184 that is housed in the mainlocking hole 162 at a moving position. A portion of the movable body 181including at least the housed end portion 184 is slidably fitted intothe main locking hole 162 to suppress the leaking of the working oilfrom the housing rotor 11 to the outside via the hole 162. In theembodiment, the housed end portion 184 has a circular flat tip surface184 a that is substantially concentric with a cross-sectional surface ofthe main locking hole 162.

An annular flange-shaped retaining portion 185 is provided between bothend portions 183 and 184 of the movable body 181. Herein, stopperportions 162 b and 162 c are formed on both sides of the main lockinghole 162 to interpose the retaining portion 185 therebetween in adirection of movement of the movable body 181. The stopper portions 162b and 162 c can lock the retaining portion 185 depending on the movingposition of the movable body 181.

When the movable body 181 having the above-described configuration movesto a blocking position Lc as illustrated in FIGS. 6, 7 and 13, themovable body 181 substantially blocks an opening 162 d on a vane rotor14 side of the main locking hole 162. Because of the blockage, the mainlocking member 160 at the main locking phase Pm illustrated in FIGS. 6and 13 is blocked by the tip surface 184 a of the movable body 181, andthus the main locking member 160 is removed from the main locking hole162, that is, the locking of the rotational phase is released. At thistime, the retaining portion 185 is locked by the stopper portion 162 b,and thus the movable body 181 in the main locking hole 162 is preventedfrom falling out from the opening 162 d.

In contrast, when the movable body 181 moves to an open position Lo asillustrated in FIGS. 5, 8 and 12, which is shifted from the blockingposition Lc to the side opposite to the vane rotor 14, the movable body181 opens the opening 162 d. Because of the opening, the main lockingmember 160 at the main locking phase Pm as illustrated in FIGS. 5 and 12is inserted into the main locking hole 162 until being brought intocontact with the tip surface 184 a of the movable body 181, and thus therotational phase is locked. At this time, the retaining portion 185 islocked by the stopper portion 162 c particularly at a maximum openposition Lomax of the open position Lo, at which the main locking hole162 is the most widely opened, and thus the movable body 181 in the mainlocking hole 162 is prevented from falling out from the opening 162 a.

As illustrated in FIGS. 1 and 11, the driving source 182 in theembodiment is a linear solenoid, and has a fixation casing 189, a driveshaft 186 and a drive coil 188. The hollow metallic fixation casing 189is fixed to a stationary component (for example, a cylinder head or thelike) of the internal combustion engine. The columnar metallic driveshaft 186 is disposed outside the housing rotor 11, and is supported bythe stationary component via the fixation casing 189. The drive coil 188is constituted by winding a metallic wire, and is housed inside thefixation casing 189. The drive shaft 186 is driven to reciprocate alongthe radial direction of the rotors 11 and 14 based on a control ofenergization of the drive coil 188.

As illustrated in FIGS. 12 and 13, a tip portion 187 is formed with acylindrical outer circumferential surface 187 a in the drive shaft 186of the embodiment, and the tip portion 187 can advance and retreat withrespect to a rotation region Ar of the protruding end portion 183 of themovable body 181 that rotates integrally with the housing rotor 11.Herein, the rotation region Ar is defined by deriving a locus of thetaper-shaped protruding end portion 183 rotating with the housing rotor11 across the entire moving positions of the movable body 181.

As illustrated in FIGS. 6, 13 and 14, when the drive shaft 186 is drivento an advance position Li at which the tip portion 187 advances into therotation region Ar, the outer circumferential surface 187 a of the tipportion 187 is brought into contact with the protruding end portion 183as the housing rotor 11 rotates. Herein, in particular, when the movablebody 181 is present at the maximum open position Lomax as illustrated inFIG. 14, and the cylindrical outer circumferential surface 187 a isbrought into contact with the taper-shaped outer circumferential surface183 a, the protruding end portion 183 receives a partial force F thatacts toward the blocking position Lc in a direction of movement of themovable body 181, which is parallel to the axis of the rotors 11 and 14.At this time, the protruding end portion 183 at the main locking phasePm is pressed toward the blocking position Lc by the drive shaft 186. Asa result, the housed end portion 184 presses the main locking member 160against the restoring force of the main elastic member 163, and thus themain locking member 160 can be removed from the main locking hole 162.

In contrast, as illustrated in FIGS. 5, 7, 8 and 12, when the driveshaft 186 is driven to a retreat position Le at which the tip portion187 withdraws from the rotation region Ar, the end portions 187 and 183are not brought into contact with each other regardless of the rotationof the housing rotor 11. Herein, in particular, the housed end portion184 at the main locking phase Pm as illustrated in FIG. 5 is pressed bya pressure of the working oil in the advance chamber 22 or the retardchamber 26, or by the main locking member 160 which receives therestoring force of the main elastic member 163. Accordingly, the movablebody 181 is driven to the open position Lo. At this time, the movablebody 181 is pressed and can be driven to the maximum open position Lomaxby the main locking member 160 that receives the restoring force of themain elastic member 163 in a state where a pressure loss in the mainlocking release chamber 161 occurs.

As illustrated in FIG. 1, the control circuit 80 is electricallyconnected to the drive coil 188. During the starting of the internalcombustion engine, the control circuit 80 as “determination portion”determines which one of an engine temperature and a specific temperatureTs (refer to FIGS. 16 and 17 to be described later) is high, andcontrols the energization of the drive coil 188 based on thedetermination result. Thus, the control circuit 80 determines a warmstart when the engine temperature is equal to or higher than thespecific temperature and a cold start when the engine temperature islower than the specific temperature. Herein, the engine temperature isacquired based on information of a temperature detected by a temperaturesensor such as a coolant temperature sensor or an oil temperature sensorwhich is mounted on the vehicle. For example, the specific temperatureTs is preset to a temperature in a range of 40° C. to 60° C. toappropriately discriminate a warm start at the specific temperature Tsor higher from a cold start at less than the specific temperature Ts.However, the specific temperature Ts may be preset to anothertemperature.

(Action of Variable Torque on Vane Rotor)

Subsequently, a variable torque which acts on the vane rotor 14 from thecam shaft 2 will be described.

During the rotation of the internal combustion engine, the variabletorque acts on the vane rotor 14 by a spring reaction force from theintake valve 9 the opening and closing of which is driven by the camshaft 2. As exemplified in FIG. 15, the variable torque alternatesbetween a negative torque that acts in an advance direction relative tothe housing rotor 11 and a positive torque that acts in a retarddirection relative to the housing rotor 11. With regard to the variabletorque of the embodiment, a positive peak torque becomes greater than anegative peak torque due to friction between the cam shaft 2 and thebearing thereof and the like, and an average torque is offset to apositive torque side (in a retard direction).

(Biasing Structure of Vane Rotor)

Subsequently, a biasing structure for biasing the vane rotor 14 towardthe sub locking phase Ps will be described.

In the rotation drive unit 10 which is illustrated in FIG. 1, the rotors11 and 14 are respectively provided with locking pins 110 and 146. Thefirst locking pin 110 is formed in a columnar shape on the front plate15 to protrude toward a side opposite to the shoe ring 12 in the axialdirection. The second locking pin 146 is formed in a columnar shape onthe rotary shaft 140 to protrude in the axial direction toward the plate15 from an arm plate 147 substantially in parallel to the front plate15. The locking pins 110 and 146 are disposed at locations that areoffset at substantially the same distance from rotation center lines ofthe rotors 11 and 14, respectively, and are shifted in the axialdirection from each other.

An advance angle elastic member 19 is disposed between the front plate15 and the arm plate 147. The advance angle elastic member 19 is formedby winding a metallic plate into a helical shape on substantially thesame plane, and the center of the helical shape is aligned with therotation center lines of the rotors 11 and 14. An innermostcircumferential portion of the advance angle elastic member 19 ismounted in a winding manner on an outer circumferential portion of therotary shaft 140. An outermost circumferential portion of the advanceangle elastic member 19 is bent in a U shape to form a locking portion190. Any one of the locking pins 110 and 146 can lock the lockingportion 190 based on the rotational phase.

In the aforementioned configuration, when the rotational phase changesto an angle retarded more than the sub locking phase Ps, that is, anangle between the locking phases Ps and Pm, the locking portion 190 islocked by the first locking pin 110. At this time, since the secondlocking pin 146 deviates from the locking portion 190, a restoring forceof the advance angle elastic member 19 generated from a torsionalelastic deformation acts on the vane rotor 14 as a rotational torque inthe advance direction relative to the housing rotor 11. That is, thevane rotor 14 is biased in the advance direction toward the sub lockingphase Ps. The restoring force of the advance angle elastic member 19 ispreset to be greater than an average value of the variable torque (referto FIG. 15) that is offset in the retard direction between the lockingphases Ps and Pm. In contrast, when the rotational phase changes to anangle advanced more than the sub locking phase Ps, the locking portion190 is locked by the second locking pin 146. At this time, since thefirst locking pin 110 deviates from the locking portion 190, the biasingof the vane rotor 14 by the advance angle elastic member 19 is limited.

(Operation)

Subsequently, the entire operation of the apparatus 1 according to acontrol process of the control circuit 80 will be described.

(1) Normal Operation

During a normal operation of the internal combustion engine after thestart and the complete combustion, the spool 68 moves to any one ofregions Rr, Ra and Rh. At this time, as illustrated in FIGS. 16 and 17,the pump 4 continuously supplies the working oil at a high pressureaccording to a rotational speed of the internal combustion engine. As aresult, the main locking member 160 is removed from the main lockinghole 162 against the restoring force of the main elastic member 163 by apressure of the working oil introduced into the main locking releasechamber 161 (refer to FIG. 8). In addition, the sub locking member 170is removed from the sub locking hole 172 and the limiting groove 174against the restoring force of the sub elastic member 173 by a pressureof the working oil introduced into the sub locking release chamber 171(refer to FIG. 8). As results of the removals, the releases of bothlocking phases Pm and Ps are maintained, and valve timing isappropriately adjusted based on a moving position of the spool 68, whichcorresponds to any one of the regions Rr, Ra and Rh.

During the normal operation, since a pressure of the main lockingrelease chamber 161 acts on the main locking member 160, the release ofthe main locking phase Pm is maintained regardless of a moving positionof the movable body 181. During the normal operation, since the driveshaft 186 is driven to the retreat position Le by a control ofenergization of the drive coil 188, the movable body 181 receives a highpressure of the working oil in the advance chamber 22 or the retardchamber 26 to move to the maximum open position Lomax (refer to FIG. 8).

(2) Stop and Start

As illustrated in FIGS. 16 and 17, an operation of the internalcombustion engine is changed to a stop operation from a normal operationbased on a stop command such as an OFF command of the engine switch SWor an idle stop command of the idle stop system ISS. During the stopoperation, before the internal combustion engine inertially rotates by afuel cut-off, the spool 68 moves to a locking region R1. At this time,the pump 4 continuously supplies the working oil at a high pressureaccording to a rotational speed of the internal combustion engine.Accordingly, the rotational phase changes to the main locking phase Pmas the most retarded angle phase by a pressure of the working oil in theretard chambers 26, 27 and 28.

During the stop operation after the rotational phase changes to the mainlocking phase Pm, the internal combustion engine inertially rotates. Asillustrated in FIGS. 16 and 17, the pressure of the working oil suppliedfrom the pump 4 gradually decreases as an inertial rotational speeddecreases. At this time, the pressure of the working oil in the mainlocking release chamber 161 decreases, and the drive shaft 186 is drivento the retreat position Le by a control of energization to the drivecoil 188. Accordingly, the main locking member 160 which receives therestoring force of the main elastic member 163 is inserted into the mainlocking hole 162 to press the movable body 181 to the maximum openposition Lomax (refer to FIG. 5). In addition, since the pressure of theworking oil in the sub locking release chamber 171 decreases, the sublocking member 170 which receives the restoring force of the sub elasticmember 173 is brought into contact with the rear plate 13 outside thesub locking hole 172 and the limiting groove 174 (refer to FIG. 5). Asresults of the inserting and the contact, the internal combustion enginecompletely stops in a state where the rotational phase is locked at themain locking phase Pm.

As illustrated in FIGS. 16 and 17, the operation of the internalcombustion engine at the stop is changed to a starting operation basedon a starting command such as an ON command of the engine switch SW or are-starting command of the idle stop system ISS, and thus cranking isstarted. During the starting operation, the control circuit 80 executessteps S101 to S104 which are illustrated in FIG. 18. Specifically, anengine temperature is acquired (S101), and then it is determined whichone of the acquired engine temperature and the specific temperature Tsis high (S102). In other words, the control circuit 80 determineswhether the internal combustion engine is in a cold start.

When it is determined that the engine temperature is equal to or higherthan the specific temperature Ts (i.e., a warm start as shown in FIG.16), the drive shaft 186 is driven to the retreat position Le by acontrol of energization of drive coil 188 (S103) during the warm start.At this time, the movable body 181 at the maximum open position Lomax isnot pressed by the drive shaft 186, and the movable body 181 ismaintained at substantially the same position Lomax (refer to FIGS. 5and 12). At this time, the moving position of the spool 68 is retainedin the locking region R1, and the pump 4 substantially stops the supplyof the working oil. Accordingly, the main locking member 160, whichreceives the restoring force of the main elastic member 163 in a statewhere a pressure loss in the main locking release chamber 161 occurs,maintains the inserting into the main locking hole 162 (refer to FIG.5). In addition, the sub locking member 170, which receives therestoring force of the sub elastic member 173 in a state where apressure loss in the sub locking release chamber 171 occurs, is broughtinto contact with the rear plate 13 outside the sub locking hole 172 andthe limiting groove 174 (refer to FIG. 5). As results of the maintenanceof the inserting and the contact, as illustrated in FIG. 16, theinternal combustion engine undergoes a complete combustion in a statewhere the locking of the rotational phase is retained at the mainlocking phase Pm.

In contrast, when it is determined that the engine temperature is lowerthan the specific temperature is (i.e., a cold start as shown in FIG.17), the drive shaft 186 is driven to the advance position Li by acontrol of electrification of the drive coil 188 (S104) during the coldstart. At this time, as the housing rotor 11 rotates, the movable body181 at the maximum open position Lomax is pressed by the drive shaft 186in contact therewith, and thus the movable body 181 is driven to theblocking position Lc (refer to FIGS. 6 and 13). At this time, the movingposition of the spool 68 is retained in the locking region R1, and thepump 4 substantially stops the supply of the working oil. Accordingly,in a state where a pressure loss in the main locking release chamber 161occurs, the movable body 181 at the blocking position Lc presses themain locking member 160 against the restoring force of the main elasticmember 163, and thus the main locking member 160 is removed from themain locking hole 162 (refer to FIG. 6). In addition, the sub lockingmember 170, which receives the restoring force of the sub elastic member173 in a state where a pressure loss in the sub locking release chamber171 occurs, is brought into contact with the rear plate 13 outside thesub locking hole 172 and the limiting groove 174.

During the cold start during which the locking of the rotational phaseis released from the locking phases Pm and Ps by the removal and thecontact, the vane rotor 14 rotates in the advance direction relative tothe housing rotor 11 by an action of the negative torque. As a result,when the rotational phase advances from the main locking phase Pm, thesub locking member 170, which receives the restoring force of the subelastic member 173 in a state where the pressure loss in the sub lockingrelease chamber 171 occurs, enters the limiting groove 174. Accordingly,even though the vane rotor 14 rotates in the retard direction relativeto the housing rotor 11 by an action of the positive torque, asillustrated in FIG. 17, the rotational phase is limited not to return tothe main locking phase Pm.

The movable body 181 is pressed by the drive shaft 186, therebyreleasing the locking, and the rotational phase advances from the mainlocking phase Pm. Thereafter, the drive shaft 186 is not alwaysnecessary to maintain at the advance position Li. In the embodiment asillustrated in FIG. 17, the drive shaft 186 is retained at the advanceposition Li until the internal combustion engine undergoes one rotationfrom cranking, and the drive shaft 186 is driven to the retreat positionLe after one rotation. However, for example, the drive shaft 186 may becontinuously retained at the advance position Li during the cranking.

Thereafter, when the rotational phase further advances by the action ofthe negative torque and changes to the sub locking position Ps, the sublocking member 170, which receives the restoring force of the subelastic member 173 in a state where the pressure loss in the sub lockingrelease chamber 171 occurs, is inserted into the sub locking hole 172(refer to FIG. 7). At this time, the main locking member 160, whichreceives the restoring force of the main elastic member 163 in a statewhere the pressure loss in the main locking release chamber 161 occurs,is brought into contact with the rear plate 13 outside the main lockinghole 162 (refer to FIG. 7). As results of the inserting and the contact,as illustrated in FIG. 17, the internal combustion engine undergoes acomplete combustion in a state where the locking of the rotational phaseis switched to the locking at the sub locking phase Ps.

(Operation Effect)

Hereinafter, operation effects of the apparatus 1 described above willbe described.

In the apparatus 1, during the warm start of the internal combustionengine during which it is determined that the engine temperature isequal to or higher than the specific temperature Ts, the movable body181, which opens or closes the main locking hole 162 by reciprocating inthe main locking hole 162, is maintained at the open position Lo. As aresult, since the inserting of the main locking member 160 into the mainlocking hole 162 is maintained at the main locking phase Pm which isreached during the starting of the internal combustion engine, therotational phase remains locked at the main locking phase Pm. Herein, atthe main locking phase Pm at which the intake valve 9 is closed attiming later than when the piston 8 reaches the bottom dead center BDCof the cylinder 7, gas in the cylinder 7 is pushed into an intake systemas the piston 8 lifts up after the bottom dead center, and thus anactual compression ratio decreases (referred to as a decompressioneffect). Accordingly, during the warm start, for example, even though are-start is frequently repeated by the idle stop system ISS, the lockingof the rotational phase is retained at the main locking phase Pm, andoccurrence of a starting failure is suppressed.

In contrast, during the cold start of the internal combustion engineduring which it is determined that the engine temperature is lower thanthe specific temperature Ts, the movable body 181 is driven to theblocking position Lc. Since the main locking member 160 is removed fromthe main locking hole 162 at the main locking phase Pm which is reachedduring the starting of the internal combustion engine, the locking ofthe rotational phase is released. At this time, the vane rotor 14, whichreceives a variable torque from the cam shaft 2, rotates in the advancedirection relative to the housing rotor 11, and thus the rotationalphase changes to the sub locking phase Ps advanced more than the mainlocking phase Pm. As a result, the sub locking member 170 is insertedinto the sub locking hole 172 and the rotational phase is locked at thesub locking phase Ps, and thus a closing timing of the intake valvebecomes as quickly as possible. Accordingly, the amount of gas beingpushed out of the cylinder 7 decreases, and a temperature of the gasincreases together with the actual compression ratio. During the coldstart after stop under a cold condition, for example, even during astart after the vehicle is soaked for a long time under an extremelycold temperature condition or even during a re-start after the vehicletemporarily stops or completely stops by the idle stop system ISS,ignitability improves and startability can be ensured.

According to the aforementioned characteristics of the apparatus 1, astart optimized for the engine temperature can be realized.

During the cold start, the drive shaft 186 outside the housing rotor 11presses the protruding end portion 183 of the movable body 181 at theopen position Lo, which protrudes to the outside of the housing rotor 11from the main locking hole 162. As a result, not only the movable body181 is reliably driven to the blocking position Lc so that the lockingof the rotational phase can be released, but also the drive shaft 186 isprevented from interfering with a rotation of the vane rotor 14 in thehousing rotor 11 relative to the housing rotor 11 so that the rotationalphase can smoothly change to the sub locking phase Ps. Accordingly, atime period which it takes from cranking during which a variable torqueis generated during cranking of the cold start of the internalcombustion engine until when the rotational phase is locked at the sublocking phase Ps can be shortened, and thus reliability can be improvedparticularly in cold startability.

Furthermore, since the movable body 181 reciprocates in a directionangled relative to the axis of the rotors 11 and 14, that is, adirection in which a centrifugal force acts, an impact of thecentrifugal force on the reciprocating motion becomes small.Accordingly, the movable body 181 can quickly move to the open positionLo at which the locking of the rotational phase is retained at the mainlocking phase Pm, or to the blocking position Lc at which the locking ofthe rotational phase is released. As a result, when the rotational phaseis switched to a rotational phase optimized for each of the warm startand the cold start, responsiveness can be improved.

Furthermore, during the warm start, the drive shaft 186 withdraws fromthe rotation region Ar of the protruding end portion 183, and thus themovable body 181 is not pressed by the drive shaft 186 and can bereliably maintained at the open position Lo. In contrast, during thecold start, the drive shaft 186 supported by the stationary component ofthe internal combustion engine advances into the rotation region Ar ofthe protruding end portion 183, and thus the movable body 181 is broughtinto contact with the outer circumferential surface 183 a of theprotruding end portion 183 as the housing rotor 11 rotates. At thistime, since the drive shaft 186 is brought into contact with thetaper-shaped outer circumferential surface 183 a of the protruding endportion 183 the diameter of which is gradually decreases toward thedistal end, the movable body 181 receives a partial force from the driveshaft 186 in the direction of the movement of the movable body 181 whichis parallel to the axis of the rotors 11 and 14, and the movable body181 can be reliably pressed and driven toward the blocking position Lc.In addition, even though the columnar movable body 181 rotates aroundthe center line of the cylindrical main locking hole 162, a contactangle of the drive shaft 186 with respect to the taper-shaped outercircumferential surface 183 a is substantially constant, and thus themovable body 181 can be stably pressed toward the blocking position Lc.Accordingly, the movable body 181 can accurately move to the openposition at which the locking of the rotational phase is retained at themain locking position Pm, or to the blocking position Lc at which thelocking of the rotational phase is released. As a result, when therotational phase is switched to a rotational phase optimized for each ofthe warm start and the cold start, reliability can be improved.

In addition, when the rotational phase of the vane rotor 14 is betweenthe main locking phase Pm and the sub locking phase Ps, the advanceangle elastic member 19 biases the vane rotor 14 in the advancedirection relative to the housing rotor 11. Accordingly, during the coldstart of the internal combustion engine, the vane rotor 14 receives avariable torque as well as a biasing force of the advance angle elasticmember 19, and thus the vane rotor 14 can quickly change the rotationalphase relative to the housing rotor 11 to the sub locking phase Ps. As aresult, a time period which it takes from when a variable torque isgenerated during cranking of the cold start of the internal combustionengine until the rotational phase is locked at the sub locking phase Pscan be shortened, and thus reliability can be improved particularly incold startability.

Second Embodiment

As illustrated in FIG. 19, the Second Embodiment of the presentdisclosure is a modification example of the First Embodiment. A drivingsource 2182 of the Second Embodiment can drive the drive shaft 186toward only the advance position Li based on a control of energizationof the drive coil 188. In a housing rotor 2011 of the Second Embodiment,a rear plate 2013 is integrally provided with a sliding contact surface2130 and a parking surface 2132.

Specifically, the sliding contact surface 2130 is provided on a platecam 2134 that protrudes in a direction parallel to the axis of thehousing rotor 2011 toward the outside of the housing rotor 2011 from therear plate 2013. The sliding contact surface 2130 is disposed to beshifted from the protruding end portion 183 in a rotational direction ofthe rotors 11 and 14, and the sliding contact surface is laid at leastbetween an innermost circumferential edge and an outermostcircumferential edge of the rotation region Ar. The sliding contactsurface 2130 is formed to be an inclined surface that is substantiallyin parallel to the axis of the rotors 11 and 14 and is angled relativeto a radial direction of the rotors 11 and 14 at an angle of 30° to 40°.

The parking surface 2132 is provided on the plate cam 2134 to beadjacent to the sliding contact surface 2130. The parking surface 2132is disposed to be shifted from the protruding end portion 183 in arotational direction of the rotors 11 and 14. The parking surface 2132is formed in an inclined surface that is substantially in parallel tothe axis of the rotors 11 and 14 and is angled relative to the radialdirection of the rotors 11 and 14 at an angle of approximately 90°.

In such a configuration, when the drive coil 188 is not energized, thedriving source 2182 allows movement of the drive shaft 186 by an actionof an external force. At this time, in particular, when the drive shaft186 is present at the advance position Li, as illustrated in FIG. 20,the tip portion 187 is brought into contact with the sliding contactsurface 2130 as the housing rotor 2011 rotates, and thus the tip portion187 receives a partial force F′ as an external force, which acts towardthe retreat position Le. As a result, as the housing rotor 2011continues to rotate, the drive shaft 186 is driven toward the retreatposition Le in a state where the drive shaft 186 is in slide contactwith the sliding contact surface 2130, and as illustrated in FIG. 21,the drive shaft 186 reaches the retreat position Le to be in contactwith the parking surface 2132. As far as a control of energization ofthe drive coil 188 is not started, the drive shaft 186 which reaches theretreat position Le maintains a state of being parked at the retreatposition Le, and is brought into slide contact with the parking surface2132 per every rotation of the housing rotor 2011. In contrast, when thedrive shaft 186 is present at the retreat position Le, and a control ofelectrification of the drive coil 188 is started, the drive shaft 186 isdriven toward the advance position Li as far as the drive shaft 186 isnot brought into contact with the sliding contact surface 2130 by therotation of the housing rotor 2011.

In the Second Embodiment, during the normal start, the stop and the warmstart, the drive coil 188 is not energized, and thus the drive shaft 186maintains a state of being parked at the retreat position Le. Incontrast, during the cold start in the Second Embodiment, energizationof the drive coil 188 is controlled, and thus the drive shaft 186 isdriven to the advance position Li. At this time, in particular, in theSecond Embodiment, until the locking of the rotational phase is releasedby the drive shaft 186 that reaches the advance position Li, and therotational phase is advanced from the main locking phase Pm, timing ofstarting energization to the drive coil 188 is controlled in such amanner that the drive shaft 186 is not brought into contact with thesliding contact surface 2130. In addition, in the Second Embodiment,after the rotational phase is advanced from the main locking phase Pm,timing of stopping energization of the drive coil 188 is controlled insuch a manner that the drive shaft 186 can be driven toward the retreatposition Le by slide contact between the drive shaft 186 and the slidingcontact surface 2130.

According to the Second Embodiment described up to now, even though thedriving source 2182 is not energized, the drive shaft 186 can bemechanically driven to the retreat position Le. Accordingly, the drivingsource 2182 can be downsized and simplified, and the rotational phaseduring the cold start is reliably switched, and thus reliability can beimproved.

Other Embodiments

As such, a plurality of the embodiments of the present disclosure aredescribed. However, it is not meant that the present disclosure islimited to the embodiments. Various embodiments are applicable insofaras the various embodiments do not depart from the scope of the presentdisclosure.

Specifically, in a First Modification Example of the First and SecondEmbodiments, the movable body 181 may reciprocate in a directionparallel to the radial direction of the rotors 11, 2011 and 14. In FirstModification Example, for example, the main locking hole 162 can beformed to pass through the shoe ring 12 along the direction parallel tothe radial direction of the rotors 11, 2011 and 14, and the main lockingmember 160 can also reciprocate along the direction parallel to theradial direction thereof. In the First Modification Example of theSecond Embodiment, for example, the sliding contact surface 2130 isformed to be an inclined surface that is angled relative to the axis ofthe rotors 2011 and 14.

In a Second Modification Example of the First Embodiment, the lockingmembers 160 and 170 may be supported by the housing rotor 11, and thelimiting groove 174 and the locking holes 162 and 172 may be formed inthe vane rotor 14. In the Second Modification Example, for example, thedriving source 182 is built in the vane rotor 14 which is a rotationsystem, and the drive shaft 186 is supported by the rotor 14.

In a Third Modification Example of the First and Second Embodiments, asillustrated in a modification example of FIG. 22, the protruding endportion 183 may be provided with a flat inclined surface 183 b thatinclines with respect to the center line of the movable body 181, andthe drive shaft 186 may be brought into contact with the inclinedsurface 183 b as the housing rotors 11 and 2011 rotate. In a FourthModification Example of the First and Second Embodiments, the protrudingend portion 183 may protrude to the outside of the housing rotors 11 and2011 from the main locking hole 162 at least at the open position Lo.For example, the protruding end portion 183 may be drawn into the mainlocking hole 162 at the blocking position Lc.

In a Fifth Modification Example of the First and Second Embodiments, themain locking member 160 as the “sub locking member” may be inserted intothe sub locking hole 172 at the sub locking phase Ps. In this case, theelements 170, 171 and 173 of the sub locking mechanism 17 are notrequired.

In a Sixth Modification Example of the First and Second Embodiments, forexample, a member made of rubber may be adopted as the elastic members163 and 173 in addition to metallic springs other than the coil spring.In a Seventh Modification Example of the First and Second Embodiments,an electrically driven pump may be adopted as the pump 4, and theelectrically driven pump can start supplying the working oil at acomplete combustion of the internal combustion engine or at any time.

In an Eighth Modification Example of the First and Second Embodiments,if the main locking phase Pm is a rotation phase at which the intakevalve 9 is closed at timing later than when the piston 8 reaches thebottom dead center BDC of the cylinder 7, the main locking phase Pm maybe set to be advanced more than the most retarded angle phase. In aNinth Modification Example of the First and Second Embodiments, the sublocking phase Ps may be set to a rotational phase at which the intakevale 9 is closed at as earlier timing as possible than when the piston 8reaches the bottom dead center BDC of the cylinder 7 of the internalcombustion engine.

In a Tenth Modification Example of the First and Second Embodiments, theadvance angle elastic member 19 may not be provided. In this case, themovement of the spool 68 into the locking region R1 and the inertialrotation of the internal combustion engine are performed in a reversesequence. In an Eleventh Modification Example of the First and SecondEmbodiments, when the internal combustion engine is stopped based on anOFF command of the switch SW, the rotational phase is locked at the sublocking phase Ps, and then when the internal combustion engine startsbased on an ON command of the switch SW, the locking of the rotationalphase at the phase Ps may be realized as it is. Alternatively, in aTwelfth Modification Example of the First and Second Embodiments, whenthe internal combustion engine is stopped based on an idle stop command,the rotational phase is locked at the sub locking phase Ps, and thenwhen the internal combustion engine starts based on a re-startingcommand, the locking of the rotational phase at the phase Ps may berealized as it is.

What is claimed is:
 1. A valve timing adjustment apparatus that adjustsvalve timing of an intake valve, which opens and closes a cylinder of aninternal combustion engine, by a pressure of a working fluid, the valvetiming adjustment apparatus comprising: a housing rotor that rotates inconnection with a crank shaft of the internal combustion engine; a vanerotor that rotates in connection with a cam shaft of the internalcombustion engine, a rotational phase of the vane rotor relative to thehousing rotor being changed by receiving the pressure of the workingfluid in the housing rotor; a main locking portion that has a mainlocking member and a main locking hole, the main locking portion lockingthe rotational phase to a main locking phase, at which the intake valveis closed at timing later than when a piston in the cylinder reaches abottom dead center of the cylinder, by inserting the main locking memberinto the main locking hole when the rotational phase is the main lockingphase during the starting of the internal combustion engine; a sublocking portion that has a sub locking member and a sub locking hole,the sub locking portion locking the rotational phase to a sub lockingphase, which is advanced more than the main locking phase, by insertingthe sub locking member into the sub locking hole when the rotationalphase is changed from the main locking phase to the sub locking phaseduring the starting of the internal combustion engine; a movable bodythat is disposed in the main locking hole to reciprocate between an openposition at which the movable body opens the main locking hole and ablocking position at which the movable body blocks the main lockinghole; a determination portion that determines a warm start when atemperature of the internal combustion engine is equal to or higher thana specific temperature and a cold start when a temperature of theinternal combustion engine is lower than the specific temperature; and adriving source that maintains the movable body at the open position, atwhich the main locking member is inserted into the main locking hole,when the determination portion determines the warm start, and drives themovable body to the blocking position, at which the main locking memberis removed from the main locking hole, when the determination portiondetermines the cold start.
 2. The valve timing adjustment apparatusaccording to claim 1, wherein the movable body has a protruding endportion that protrudes to an outside of the housing rotor from the mainlocking hole when the movable body is at the open position, and thedriving source has a drive shaft disposed outside the housing rotor thatpresses the protruding end portion at the open position toward theblocking position during the cold start.
 3. The valve timing adjustmentapparatus according to claim 2, wherein the housing rotor and the vanerotor rotate around an axis, the movable body reciprocates in adirection parallel to the axis of the housing rotor and the vane rotor,the protruding end portion has a tapered outer circumferential surfacehaving a diameter that decreases toward a distal end of the protrudingend portion, the drive shaft is supported by a stationary component ofthe internal combustion engine, and the driving source withdraws thedrive shaft from a rotation region of the protruding end portion duringthe warm start and advances the drive shaft into the rotation regionduring the cold start.
 4. The valve timing adjustment apparatusaccording to claim 3, wherein the housing rotor integrally has a slidingcontact surface which is an inclined surface angled relative to a radialdirection of the housing rotor and the vane rotor, and the drive shaftis brought into sliding contact with the sliding contact surface anddriven from an advance position inside of the rotation region to aretreat position outside of the rotation region as the housing rotorrotates.
 5. The valve timing adjustment apparatus according to claim 1,wherein the housing rotor and the vane rotor rotate around an axis, andthe movable body reciprocates in a direction parallel to the axis of thehousing rotor and the vane rotor.
 6. The valve timing adjustmentapparatus according to claim 1, further comprising: an advance angleelastic member that biases the vane rotor in an advance directionrelative to the housing rotor when the rotational phase of the vanerotor is between the main locking phase and the sub locking phase.